502 On Luminous Meteors and Temporary Stars. 



the orbit of Mercury. TYere the space enclosed by Venus's orbit 

 assigned to them for their revohitions, they could not avoid send- 

 ing us during the night, several hundred times as much reflected 

 light as we receive from our full moon. It is moreover difficult 

 to imagine that the meteoric showers can observe an almost exact 

 uniformity in falling at all times and in all parts of the sun^s 

 surface. For the continual precipitation of these meteorites, 

 Professor Thomson finds a resisting medium necessary ; but it 

 would seem that the chemical changes which such a fluid may be 

 expected to undergo when condensed at the sun's surface, would 

 account in a more simple manner for the illumination of our 

 system. 



It appears, however, that the resistance of a space-pervading 

 medium must occasionally lead to the occurrence of stupendous 

 meteoric scenes among the numerous systems composing our 

 universe. Each primary and secondary planet, by impercept- 

 ible contractions of their orbits dm'ing innumerable years, must 

 ultimately arrive in the immediate vicinity of their respective 

 central spheres, and must perform their last revolutions through 

 the dense luciferous atmospheres collected aromid the latter. A 

 satellite in such a condition could not end its career as one vast 

 meteor, for it must be reduced to an unstable equilibrium by 

 the attraction of the primary; and, by a sudden dismember- 

 ment, it would be converted into innumerable fragments. This 

 change would evidently cause the meteoric illumination to be 

 exhibited on a more extensive scale; but a constant decline 

 would be inevitable as the fragmentary part, forming a 

 flat circular ring, became less capable of rendering the sether 

 luminous. In dark systems such occurrences would be most 

 likely to attract the attention of an observer in very distant 

 abodes of creation ; and on comparing the necessary deductions 

 from this theory with the recorded phfenomena of temporaiy 

 stars, it seems difficult to avoid the conviction that the stellar 

 curiosities which called forth such astonishment in 1572, 1604, 

 and other times, were the result of great meteoric exhibitions 

 occurring in the fetherial atmospheres of dark central bodies as 

 they were traversed by the ruins of dilapidated worlds. 



Fi'om the appeamnce of meteors and temporary stars, we must 

 therefore conclude that photospheres envelope, not only suns, 

 but also planets and dark central spheres, whose attraction is 

 not sufficient to maintain them in a constantly luminous con- 

 dition. Perhaps a closer relation between the atmospheric ap- 

 pendages of all these great bodies may be revealed, if we consider 

 that the lower envelope of the sun is non-luminous, and that 

 meteoric stones cease to give light when they enter the lower 

 regions of our atmosphere. But I must defer a further consi- 



